Lamk M. Lamki

Phase I trial of liposomal muramyl tripeptide phosphatidylethanolamine in cancer patients.

Twenty-eight evaluable patients with metastatic cancer refractory to standard therapy received escalating doses of muramyl tripeptide phosphatidylethanolamine (MTP-PE) (.05 to 12 mg/m2) in phosphatidylserine (PC):phosphatidylcholine (PS) liposomes (lipid:MTP-PE) ratio 250:1). Liposomal MTP-PE (L-MTP-PE) was infused over 1 hour twice weekly; doses were escalated within individual patients every 3 weeks as tolerated for a total treatment duration of 9 weeks. Routine clinical laboratory parameters, acute phase reactants and various immunologic tests were monitored at various time points during treatment. Toxicity was moderate (less than or equal to grade II) in 24 patients with chief side effects being chills (80% of patients), fever (70%), malaise (60%), and nausea (55%). In four patients L-MTP-PE treatment was deescalated due to severe malaise and recurrent fever higher than 38.8 degrees C. The maximum-tolerated dose (MTD) was 6 mg/m2. Significant (P less than .05) increases in WBC count, absolute granulocyte count, ceruloplasmin, beta 2-microglobulin, c-reactive protein, monocyte tumoricidal activity, and serum IL-1 beta were found. Significant decreases in serum cholesterol were also observed. Clearance of intravenously (iv)-infused technetium-99 (99mTc)-labeled liposomes containing MTP-PE in four patients was biphasic; gamma camera scans revealed uptake of radiolabel in liver, spleen, lung, nasopharynx, thyroid gland, and tumor (two patients). No objective tumor regression was seen. In view of its definite immunobiologic activity and lack of major toxicity, additional phase II and adjuvant trials of L-MTP-PE are warranted.

Improved tumor localization with increasing dose of indium-111-labeled anti-carcinoembryonic antigen monoclonal antibody ZCE-025 in metastatic colorectal cancer.

Monoclonal antibodies (MoAbs) against carcinoembryonic antigen (CEA) react with human colorectal cancer cells, and when labeled with a gamma-emitting radioisotope, may help to localize known and occult metastatic disease. We tested ZCE-025 (Hybritech, Inc, San Diego), a high-affinity immune gamma globulin1 (IgG1) MoAb anti-CEA that does not react with normal granulocyte glycoproteins in a phase I/II trial to determine the reagents toxicity and its maximum efficacy in detecting metastatic colorectal cancer. Increasing doses of unlabeled ZCE-025 were mixed with 1 mg of Indium-111 (111In)-radiolabeled MoAb and administered intravenously (IV) to 34 patients who had metastatic colorectal cancer. Planar nuclear or single photon emission computed tomographic (SPECT) scans were performed 48 to 72 and 120 to 144 hours later. Total dose of MoAb and scanning sensitivity (number of imaged lesions/number of known lesions) were correlated up to 80 mg. At doses of 2.5 to 20 mg, a mean of 22% of the lesions were imaged; at 40 mg, 77% were imaged (P less than .01). Liver metastases were detected as areas of increased activity (hot) at the 40 mg dose but showed decreased MoAb uptake at lower doses. At the 40 mg dose normal liver parenchymal uptake of the labeled MoAb was lower with respect to blood pool compared with the other doses. At 80 mg, however, sensitivity of detection declined to 21%. One milligram of 111In-labeled ZCE-025 antibody coinfused with 39 mg of unlabeled antibody appeared optimal for detecting metastatic colorectal cancer, particularly in the liver. Although the exact mechanism(s) for this dose effect is currently unknown, a partial blocking effect of unlabeled antibody with a change in MoAb biodistribution may be occurring.

Imaging with indium111-labeled anticarcinoembryonic antigen monoclonal antibody ZCE-025 of recurrent colorectal or carcinoembryonic antigen-producing cancer in patients with rising serum carcinoembryonic antigen levels and occult metastases.

We tested whether nuclear imaging with indium111 (111In)-labeled murine monoclonal (MoAb) anticarcinoembryonic antigen (anti-CEA) ZCE-025 antibody could detect recurrent disease in patients with a rising serum CEA level but negative findings for computed tomographic (CT) scans of the abdomen and pelvis, chest radiograph, and colonoscopy or barium enema. Twenty patients with a history of completely resected CEA-producing adenocarcinoma (18 with colon cancer, one with breast cancer, and one with Hodgkins disease) and a rising serum CEA level were given an intravenous infusion of 2 mg of 111In-labeled ZCE-025 mixed with 38 mg of unlabeled ZCE-025. Planar and single-photon emission CT (SPECT) scans were acquired at 72 and 144 hours, and in 19 of the 20 patients these were positive. Of those 19, 13 underwent exploratory surgery, and cancer was found in 10, and two had a diagnostic biopsy, which confirmed cancer. Three patients who had negative laparotomies and all four patients who did not undergo surgery or biopsy were followed radiologically. In all seven, cancer was subsequently detected at the sites suggested by the ZCE-025 scan. Thus, tumor was confirmed in all 19 patients with positive scans. Five of 13 patients who were explored benefited from the study and the exploratory laparotomy, as disease was entirely resected in four or was subjected to definitive radiation therapy to the pelvis in the fifth. In two additional patients who were not explored, MoAb imaging resulted in definitive therapy to regionally confined recurrent disease. 111In-labeled anti-CEA MoAb ZCE-025 scanning in patients with rising CEA successfully imaged metastatic colorectal cancer that eluded detection by other methods and affected the care given to some. These results suggest an important role for 111In-labeled ZCE-025 scanning among patients with rising CEA and otherwise occult metastatic cancer.

Regression of hepatic metastases from gastrointestinal leiomyosarcoma after hepatic arterial chemoembolization.

Two patients with gastrointestinal leiomyosarcoma metastatic to the liver were treated by hepatic chemoembolization with cisplatin and polyvinyl sponge followed by hepatic arterial infusion of vinblastine. Effective palliation in terms of durable tumor regression was achieved in both patients after two chemoembolization‐infusion procedures. These results suggest that regional therapy may offer new hope for the subset of sarcoma patients who have liver metastases resistant to combination systemic chemotherapy.

Radioimmunoscintigraphy of prostate cancer

The development of hybridoma technology has increased research efforts and clinical applications in the area of radioimmunodetection. Despite the many investigative antibodies directed against prostatic tissue or prostate cancer cell lines, only two have been tested in clinical trials. A 111 In-labeled antibody directed against prostate-specific antigen, the best available serum tumor marker for prostate cancer, has shown poor sensitivity in limited clinical radioimmunoimaging trials. Monoclonal antibodies against prostatic acid phosphatase have shown better imaging results, particularly at higher antibody doses (≥40mg). The limitations of this antibody include the poor results in detecting soft tissue lesions, including the primary lesion; the development of human antimouse antibodies in 50% of the patients at doses >-40 mg; the expense of the antibody; and the fact that better results are currently attainable by other less expensive imaging modalities. If and when a more suitable antibody or fragment is developed, the prospect of improved staging and new treatments using immunologic conjugates carrying therapeutic agents may become realities. Until such time, prostatic cancer will be staged with other currently available imaging modalities and conventional therapies with their limitations will remain state of the art.

Effect of unlabelled monoclonal antibody (MoAb) on biodistribution of111indium labelled (MoAb)

We have evaluated immunoscintigraphy in cancer patients using four 111In-labelled murine monoclonal antibodies (MoAb): 96.5 (anti-P97 of melanoma), ZME-018 (anti-high molecular weight antibody of melanoma), ZCE-025 (anti-CEA for colon cancer) and PAY-276 (anti-prostatic acid phosphatase for prostatic cancer). The effect of increasing the doses of unlabelled MoAb (co-infused with 1 mg labelled MoAb) on the relative body distribution of each labelled MoAb was assessed. Localization in the liver decreased significantly in all cases, with increasing MoAb dose, except for ZME-018. Localization in other organs increased significantly as the liver activity decreased. The spleen activity, however, fell in the case of MoAb ZME-018. Blood-pool activity increased with MoAb dose in all four MoAbs. These findings correlated with the rise in the detection rate of metastases, the plasma half-life, and other pharmacokinetic parameters. However, the dose level at which this correlation occurred varied with each antibody. These data demonstrate that co-infusion of unlabelled MoAb with 111In-labelled MoAb could alter the organ distribution, pharmacokinetics and tumour uptake in a favourable manner, though the degree to which this occurs depends on the antibody in question.

Radioimmunoimaging of malignant melanoma with monoclonal antibodies

Malignant melanoma is currently the only cancer besides lung cancer that is increasing in incidence, with approximately 24,000 new cases diagnosed per year [1]. Although localized disease can be cured by surgery if discovered early, regional or disseminated disease is seldom curable. Overall response rates to single-agent or combination chemotherapy as well as overall survival have not changed appreciably over the past 15 years [2]. Therefore, the development of new diagnostic as well as therapeutic modalities for this disease remains of paramount importance.

A dichotomy in hepatic uptake of 99mTc-IDA and 99mTc-colloid.

A 60-yr-old man was admitted with a 2-mo history of weight loss, jaundice, and vague abdominal pain. Physical examination revealed hepatomegaly. Laboratory investigation confirmed hepatic dysfunction with significant elevation of alkaline phosphatase and moderate elevation of SGOT and bilirubin. A 99roTe tin colloid scan revealed a large photon-deficient area in the right lobe with at least two small cold areas in the left lobe (Fig. 1A). A 99mTc-dimethylimino-diacetic acid (HIDA) study a week later showed normal perfusion of the entire liver, and static images revealed that the area that was cold in the tin colloid scan was relatively normal in the HIDA scan (Fig. 1B) though patchy. A repeat tin colloid scan done yet another week later, confirmed the previous cold area. Ultrasonography revealed the cold area to be echogenic. The patient underwent a laparotomy because of the clinical suspicion of hepatoma. Open liver biopsy revealed no evidence of malignancy, but active cirrhosis with features of chronic hepatitis and orcein stain evidence of hepatitis B antigen. The discrepancy in the results of the two scans in this patient is explained by the presence of postnecrotic cirrhosis and large regenerative nodules made up predominantly of hepatocytes. Imino-diacetic acid (IDA) derivatives, which are lidocaine analogues, are taken up by the hepatocytes. Sulphur or tin colloid preparations are taken up by cells of the reticuloendothelial system (RES), which in the liver are predominantly Kupffer cells. A disease process that will unequally affect the function of the two cell types or disturbs their relative numbers will result in dichotomy in the radionuclide scans from the two imaging agents.